Spring-loaded lamp



March 10, 1964 J. A. RANDMER 3,124,713 SPRING-LOADED LAMP FILAMENTSUPPORT Original Filed July 23, 1956 FIG.

INVENTOR JACOB 4. KAI/V0445? Mm. /W

United States Patent 3,124,713 SPRING-LOADED LAMP FILAMENT SUPPORT JacobA. Randmer, Norwalk, C'onn., assignor to Sperry Rand Corporation, NewYork, N.Y., a corporation of Delaware Original application July 23,1956, Ser. No. 599,385, now Patent No. 3,003,633. Divided and thisapplication Aug. 28, 1961, Ser. No. 134,319

7 Claims. (Cl. 313-271) This invention relates generally to incandescentlamps provided with a light emitting filament, the invention relatingmore particularly to means for supporting the filament within the lamphousing.

The invention is disclosed herein in an embodiment adapted for anelongate tubular lamp which may be employed as an infra-red light sourcefor the photo responsive sensing unit of a record controlled businessmachine. Such a lamp employed for such a purpose is shown and describedin the co-pending application of Guillermo Perez, Philip S. Rand andJacob A. Randmer entitled Record Card Sorting Machine bearing Serial No.599,385 and filed July 23, 1956, now Letters Patent No. 3,003,633, thepresent application being a division thereof.

A lamp employed for this purpose must necessarily assume a long tubularshape of a length commensurate with the length of the record card to besensed or scanned thereby and must also provide a filament ofcorresponding length in order to illuminate the entire length of thecard with an even or uniform degree of light. It has been found thatfilaments of relatively long lengths have a tendency to sag when heateddue to heat expansion. Attempts have heretofore been made to providemeans for eliminating the sag of a filament in a tube of this type, saidmeans assuming the form of a spring member connected to one end of thefilament for keeping the filament taut under all heat conditions.However, it has been found that even with the provision of a take-upspring connected to the filament, the filament and spring is susceptibleto excessive vibration particularly when the lamp is used in equipmentprone to vibration such as, for example, the record card sorting machineof the aforesaid copending application. Excessive vibration of thefilament impairs the uniform light emitting characteristics of thefilament and also tends to put undue and unnecessary strain on thefilament adversely affecting its usefulness and long life. The device ofthe instant application minimizes the amount of vibration which can beset up in the filament by providing a support for the filament at thepoint where the filament is joined to take-up spring thereby improvingthe light emitting qualities of the filament and eliminating the strainand wear on the filament which the vibrations would otherwise cause.

It is, therefore, an object of this invention to improve upon the meansfor supporting a filament in a light emitting lamp of thecharacter-described.

It is a further object of the invention to eliminate or minimizevibration in a filament for a lamp of the character described.

It is a further object of the invention to provide a fila ment supportin the lamp of the character described of simplified design, of durableconstruction and economical to manufacture.

Further objects of the invention together with the featuresconstributing thereto and advantages accruing therefrom will be apparentfrom the following description when read in conjunction with thedrawings wherein:

FIG. 1 is a fragmentary side elevation of one end of a lamp with theenvelope partly cut away to show the filament supporting assemblycontained therein;

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FIG. 2 is a section taken along the lines 2-2 of FIG. 1;

FIG. 3 is a section taken along the lines 3--3 of FIG. 1.

As shown in the drawing, a lamp 400 comprises an evacuated envelope 410housing a ribbon filament 411, preferably of tungsten or the like, whichfilament is secured at one end to an external terminal of the lamp (notshown) and at the other end to a plate member 414. The plate 414 ispreferably formed of two flat pieces of metal having good conductingproperties and joined together, the upper and lower edges of the metalmembers being spread apart and turned inwardly to provide asubstantially round bearing surface by which the plate is slidablymounted on a supporting framework.

The supporting framework comprises a ring member 415 having lugs 416bent outwardly therefrom for contacting the inner surface of theenvelope 410 and thereby supporting the ring 415 concentrically to theaxis of the envelope. The ring 415 is made of a material such as willprovide the lugs 416 with a limited amount of yield and therebyproviding a snug fit of the ring 415 with envelopes of slightly varyingdiameters and under all heat conditions. The framework also includes aflat plate 417 of electrically conductive material which is secured tothe other external end terminal 418 of the lamp. The plate 417 isconnected to ring 415 by rods 420 on which rods the plate 414 isslidably mounted. Plates 414 and 417 are structually connected by aspring 419 preferably of tungsten or the like, and around said spring isa coil of wire 421 formed of good conductive material such as copper orthe like suitably joined to plates 414, 417 so as to provide a primaryelectrical connection between the' filament 411 and the external endterminal 418.

When the lamp is connected in a circuit and current is passed throughfilament 411, the filament expands whereupon the spring 419 causes plate414 to slide along the supporting rods 420 to take up the slack in thefilament. It will be noted that the plate 414 serves as a support forthe filament 411 at the point where it is mechanically coupled to thetake-up spring 419, and since the plate 414 is carried by frame workwhich at one end is supported rigidly by the external tube terminal 418and at the other end by a support member 415 snugly fitted to the tubeenvelope 410, any tendency of the filament and take-up spring to vibrateharmonically or otherwise, as a result of vibrations imparted to thetube envelope, is substantially suppressed. It will also be noted thatby providing two support or guide rods 420 for the slidable plate 414,the plate 414 is restricted to a single plane of motion and therebyprevents the filament 411 from rotating with the result that the planeof the filament is maintained in a fixed position in the lamp at alltimes.

From the foregoing it will be apparent that the invention as hereindisclosed and described provides a simple, efiicient and reliable meansfor supporting a filament within a tubular envelope in such a manner asto maintain the filament taut under the various heat conditionsgenerated by the lamp and also so as to substantially suppress allvibrations which may be set up in the filament from operation of theequipment in which the lamp is employed.

While there has been shown and described what is considered to be apreferred embodiment of the invention, it is of course understood thatvariations in form could be made without departing from the spirit ofthe invention, and it is intended therefore that the invention be notlimited to the exact form herein disclosed nor to anything less than thewhole of the invention as hereinbefore set forth and as hereinafterclaimed.

What is claimed and desired to be secured by Letters Patent is:

1. In a lamp of the class described comprised of a substantiallyevacuated envelope having an elongate filament supported therein andexternal terminals for connecting the lamp to a power source, means forsecuring one end of said filament to one of said terminals, a frameworkdisposed within said envelope, said framework including a portion ofelectrically conductive material secured to said other terminal andanother portion in bearing contact with the inner surface of saidenvelope, a filament support member joined to said other end of thefiiament and mounted to slide along a plane on said framework, yieldablemeans electrically connecting said support member with the electricallyconductive portion of said framework, and means connected to saidsupport member for urging said support member in a direction to stretchsaid filament.

2. The invention according to claim 1 wherein said framework includesguide rods slide fitted with said support member and disposed to providea path of movement for said support member in a direction coaxial withsaid filament.

3. The invention according to claim 1 wherein said framework includes aplurality of parallel guide rods slide fitted with said support memberand disposed to provide a path of movement for said support member in adirection coaxial with said filament.

4. The invention according to claim 1 wherein the means for urging saidsupport member comprises a tension spring connected at one end to saidelectrically conductive portion of said framework and at the other endto said slideable support member.

5. The invention according to claim 1 wherein said other portion of saidframework comprises a ring shaped member formed with outwardly bent lugsdisposed to yieldably contact the inner surface of said envelope for 4supporting said ring shaped member concentrically with said envelope.

6. The invention according to claim 1 wherein said means forelectrically connecting said support member with the electricallyconductive portion of said framework includes a coil of electricallyconductive wire and wherein said means yieldably connecting said supportmember with said framework comprises an expansion spring, said springbeing disposed Within the inner diameter of said coil of electricallyconductive wire.

7. In a lamp of the class described comprised of a substantiallyevacuated envelope having an elongate filament supported therein andexternal terminals for connecting the lamp to a power source, means forsecuring one end of said filament to one of said terminals, a frameworkdisposed within said envelope, said framework including a portion ofelectrically conductive material secured to said other terminal, anotherportion of ring shaped eonfiguration and formed with lugs projectingoutwardly therefrom to yieldably engage the inner surface of saidenvelope, and guide rods interconnecting said portions of saidframework, a filament support member joined to the other end of thefilament and slidably mounted on said guide rods, said guide rodsdefining a path of movement for said support member in a directioncoaxial with said filament, a coil of electrically conductive wireconnecting said support member with the electrically conductive portionof said framework, and a helical tension spring disposed within the boreof said coil of wire and interconnecting said support member with saidone portion of said framework for urging said support member in adirection to stretch said filament.

References Cited in the file of this patent UNITED STATES PATENTS2,672,570 Carlstrom Mar. 16, 1954

1. IN A LAMP OF THE CLASS DESCRIBED COMPRISED OF A SUBSTANTIALLYEVACUATED ENVELOPE HAVING AN ELONGATE FILAMENT SUPPORTED THEREIN ANDEXTERNAL TERMINALS FOR CONNECTING THE LAMP TO A POWER SOURCE, MEANS FORSECURING ONE END OF SAID FILAMENT TO ONE OF SAID TERMINALS, A FRAMEWORKDISPOSED WITHIN SAID ENVELOPE, SAID FRAMEWORK INCLUDING A PORTION OFELECTRICALLY CONDUCTIVE MATERIAL SECURED TO SAID OTHER TERMINAL ANDANOTHER PORTION IN BEARING CONTACT WITH THE INNER SURFACE OF SAIDENVELOPE, A FILAMENT SUPPORT MEMBER JOINED TO SAID OTHER END OF THEFILAMENT AND MOUNTED TO SLIDE ALONG A PLANE ON SAID FRAMEWORK, YIELDABLEMEANS ELECTRICALLY CONNECTING SAID SUPPORT MEMBER WITH THE ELECTRICALLYCONDUCTIVE PORTION OF SAID FRAMEWORK, AND MEANS CONNECTED TO SAIDSUPPORT MEMBER FOR URGING SAID SUPPORT MEMBER IN A DIRECTION TO STRETCHSAID FILAMENT.